Superconducting device structure with Pr-Ba-Cu-O barrier layer

Abstract

A superconducting transistor having a source region and a drain region are formed by a YBCO film on a barrier layer, which is composed of a PBCO film formed on an STO substrate. A gate electrode is disposed on the thinner wall at the back of the STO substrate. In a superconducting transistor so constructed the electric field created by the gate voltage works effectively at an interface with the barrier layer, more carriers can be drawn out relative to the applied gate voltage, and it becomes possible for a large superconduction current to flow.

What is claimed: 
     
       1. A superconducting device comprising: a source region and a drain region each comprised of an oxide superconductor;   a barrier layer having a crystalline structure similar to that of said oxide superconductor, said barrier layer having upper and lower opposite major surfaces, said source and drain regions being formed on said upper surface of said barrier layer; and   a gate electrode spanning over said source region and said drain region, said gate electrode being capable of applying an electric field to said barrier layer, wherein said gate electrode is formed below the lower surface of said barrier layer, and an insulation layer is interposed between said gate electrode and said barrier layer wherein said barrier layer is non-superconducting when a gate voltage is not applied to the gate electrode.   
     
     
       2. The superconducting device of claim 1, wherein said insulation layer is an insulating substrate, said insulating substrate having an area of reduced thickness spanning over said source and drain regions, said gate electrode being formed on said area of reduced thickness. 
     
     
       3. The superconducting device of claim 1, further comprising a semiconductor substrate interposed between said insulation layer and said gate electrode. 
     
     
       4. A superconducting device as claimed in claim 1, wherein the barrier layer comprises Pr--Ba--Cu--O. 
     
     
       5. A superconducting device comprising: a source region and a drain region each comprised of an oxide superconductor;   a barrier layer having a crystalline structure similar to that of said oxide superconductor, said barrier layer being interposed between said source and drain regions so as to form a laminar structure, wherein said laminar structure includes a side face; and   a gate electrode formed over said side face of said laminar structure, wherein said gate electrode extends over side faces of said source region, said barrier layer and said drain region which comprise said side face of said laminar structure wherein said barrier layer is non-superconducting when a gate voltage is not applied to the gate electrode.   
     
     
       6. The superconducting device of claim 5, further comprising an insulating layer on which said laminar structure is disposed. 
     
     
       7. A superconducting device as claimed in claim 5, wherein the barrier layer comprises Pr--Ba--Cu--O. 
     
     
       8. A superconducting device as claimed in claim 5, further comprising an insulating layer located between said gate electrode and said side face.